Apparatus for separating waxcontaining materials



Nov. 17, 1942. E. M. DONS ETAL 2,302,195

APPARATUS FOR SEPARATING WAX CONTAINING MATERIALS Filed Jan. 8, 1940 Z9gydmyuozi STRMN "Ax FSOLVENT 2a COOLER E I mcoInTm: g5 T X SOLVENT Z1 2520 l g g 55 :5 flaw N E? fl l'llllll'iz MW! 7 "A: 5i "g g: f I 5 :2 5 ig; is 5 l 2; v 15 I 55 COOLER 6E g i? T 1 E 16 f '32 01m SOLVENT IHEATER ;/E-& I L

' INVENTORS E. M.DONS

DEWAXED OIL B SOLVENT O G MAURO BYGMMA KYFGMJA ATTORNEY.

Patented Nov. 17, 1942 APPARATUS FOR SEPARATING WAX- CONTAININGMATERIALS Eddie M. Dons and Oswald G. Mauro, Tulsa, Okla., assignors toMid-Continent Petroleum Corporation, Tulsa, Okla, a corporation ofDelaware Application January 8, 1940, SerialNo- 312,800

6 Claims.

This invention relates to apparatus for separating wax-containingmaterials. The invention may be employed in separating wax and oil foundin various kinds of materials including mineral oils, petrolatum, slackwax and vegetable waxes. It can be conveniently used in dewaxinglubricating oils to produce low pour point lubricants, or in obtaininghigh melting point Waxes from petrolaturn, and in purifying slack wax,as well as in the treatment of other products to separate waxymaterials.

'Prior to this invention, the well recognized commercial systems forseparating wax involved the operations of cold settling, centrifuging orfiltering to separate the wax from oil. In modern refinery practice themethods regarded as most efficient include the step of chilling asolution of oil and solvent to precipitate the wax, and thereafterpassing the solution through a filter to separate the precipitated wax.

Various types of solvents have been employed in these old chilling andfiltering processes, including normally gaseous and normally liquidmaterials which aid in the precipitation of Wax and also serve asdiluents during the filtering operations. However, experience has shownthat each of the outstanding solvents, or diluents, is best adapted forcertain types of oils, and has a relatively low degree of efficiencywhen used with other oils. For example, a given solvent may be quitesatisfactory when used with heavy viscous oils, and considerably lessefiicient when used with light wax-bearing distillates, or vice versa.In actual practice, a conventional chilling and filtering plant equippedfor one kind of solvent can not be readily modified to receive adifferent solvent. As a consequence, the same solvent is usuallyemployed for difierent kinds of oil and wax, and this leads tounsatisfactory results in the ordinary commercial dewaxing plants.

Another phase of the present state of the art appears in the high costof dewaxing equipment wherein a large filtering plant is relied upon toseparate the mass of precipitated wax from the diluted oil. The usualfilters are quite expensive' and special care and attention is requiredin the operation of the filtering plant. This is true when normallyliquid solvents are employed, and the cost is, of course, materiallyincreased in a plant designed for normally gaseous solvents. Aside fromthe expense. involved in such plants, the popular solvents usuallyregarded as most desirable in the chilling andfiltering apparatus,

ing special precautions, and always a source of danger.

Furthermore, the filtering operations do not remove all of the oil fromthe wax. The large mass of precipitated wax is usually deposited on thefilter in the form of clusters of interlocked wax crystals withoil-retaining cavities inside of.

the clusters, and additional bodies of diluted oil are trapped betweenthe clusters on the filter. A substantial percentage of the oil is thusretained in the mass of wax.

Therefore, an object of the present invention is to generally improvethis art by producing a be employed to very readily remove practicallyare inflammable. and explosive materials requirall of the oil from thewax, this being an outstanding result not obtainable from any of themodern filtering operations.

Another object is to provide a single dewaxing system adapted to veryefficiently separate various different types of wax-containingmaterials, including viscous residues and comparatively lightdistillates, thereby overcoming a serious objection to the modernsystems which lack the desired flexibility and fail to provide a normaleficiency or economy in dewaxing the different products.

A further object is to eliminate the necessity of using dangerous orotherwise undesirable solvents to obtain a high efficiency. We can alsoavoid the troublesome operating conditions, such as requirements for acritical rate of chilling, or very gradual chilling, involved in the useof some of the modern solvents. The economy of very rapid chilling andpractically instantaneous precipitation of wax can be obtained in thenew apparatus.

More specifically stated, an object is to obtain all of these advantagesin a very simple continuous system wherein the wax is most efiectivelyseparated and thoroughly cleansed while it is in transit from theprecipitating station to a recovery station.

With the foregoing and other objects in view, the invention comprisesthe novel construction, combination and arrangement of parts hereinaftermore specifically described and shown in the accompanying. drawing,which illustrate one form of the invention. However, it is to beunderstood that the invention comprehends changes, variations andmodifications within the scope of the claims hereunto appended.

Briefly stated, the preferred form of the invention includes apparatusfor precipitating the wax in a solution, releasing the main body ofsolution from the wax in a dewaxing zone, and thereafter subjecting thewax to a cleansing operation in a deoiling zone wherein the traces orfilms of solution are forcibly removed from the wax.

At an initial stage, the wax-bearing material may be dissolved in asolvent and then cooled to precipitate wax particles in the solution.The density of the cooled solution is preferably greater than thedensity of the wax particles. The viscosity of the cooled solution, andthe interfacial tension existing between said wax particles and thesolution, are preferably low enough to allow the wax to freely rise inthe solution.

At a subsequent stage, there is a preliminary separation due to thediiferences in specific gravity, the relatively dense solution movingdownwardly while the wax particles rise in the solution, carrying withthem relatively small portions of the solution. At this stage, therising wax particles may be surrounded by films of the oil solution, andadditional portions of the solution will be distributed throughout themass of wax particles.

This condition is preferably followed by a cleansing operation whichseparates oily solution from the wax particles to produce a mass ofclean wax, free of the oil, etc. For example, a descending stream ofoil-solvent may be transmitted through the rising mass of wax particles,so as to forcibly scrub each wax particle, thereby dissolving the oilyfilms and removing them from the wax particles, at the same timedissolving the relatively free portions of oil or solution carried bythe mass of wax. The rising wax particles are thus subjected to a mosteffective cleansing action, and thereafter discharged from thedescending solvent. As a consequence, the wax can be obtained in aremarkably clean and pure condition, far superior to the condition ofthe wax obtained in the modern filtering apparatus.

In comparing this apparatus with the usual filtering systems wherein asolvent is sprayed onto the wax deposited on the surface of the filter,it will be observed that the so called wax cake on the filter is in theform of a compact body with oil particles trapped throughout the mass ofwax, and that the spray of solvent can not effectively remove such oil.This is quite different from the cleansing action which occurs when astream of free wax particles rises through a descending stream ofoil-solvent, which flows through the spaces between the wax particles,so as to very readily dissolve the relatively free liquid between thewax particles, and exert a forcible scrubbing and dissolving action onthe oily films adhering to these wax particles. Actual tests of the newdewaxing apparatus have shown that it can be employed to removepractically all of the oil from the wax, and so far as we are aware,this result has never been accomplished in any of the prior dewaxingsystems.

Furthermore, instead of subjecting the oil and wax to numerous differentkinds of treatments in a series of different types of apparatus, we canaccomplish all of the improved results in a simple unitary systemwherein the wax is precipitated in a continuous stream of solution, andthereafter separated by gravity to provide a stream of wax particleswhich flow through the cleansing solution.

When a solution of wax-bearing oil and solvent is cooled to precipitatewax therein, the wax particles are usually united in the form ofclusters with oil-retaining cavities therein. The specific apparatusherein described includes a device for forcibly dividing theprecipitated wax into minute particles suspended in the cold solution toform a more or less homogeneous slurry of wax and solution. The clustersare thus broken apart to release the oil solution trapped therein. Anoperation of this kind would be quite objectionable in the usualfiltering processes which require the wax to be in a condition foreflicient filtration. However, we can eliminate the special precautionsordinarily involved in filtration, and the wax can be quicklyprecipitated in either a liquid or solid condition and in fine or coarseparticles, or any kind of cluster formation. In commercial practice thisabsence of special requirements is an important advantage, as itovercomes the trouble and expense of deliberately arranging for thecritical operating conditions which produce readily filterable wax.

It is not necessary for us to break up the wax clusters, but this is aconvenient means for releasing the oil solution trapped therein, and theresultant slurry may be readily discharged into the separating zonewhere the minute wax particles rise from the relatively dense solution,and pass through the cleansing zone where each minute wax particle isexposed to the forcible cleansing action of the descending solventstream. In this manner we can positively remove and recover asubstantial percentage of oil which ordinarily remains as an impurity inthe wax.

It is to be understood that such unusal elliciency in removing andpurifying the wax also increases the yield of dewaxed oil, and in manycases the main object is to remove and recover the optimum percentage ofdewaxed oil, without resorting to expensive refining operations.

The wax may be precipitated in any desired manner and at any suitabletemperature, a low temperature being required in dewaxing lubricatingoils to produce low pour point lubricants, while much highertemperatures are usually desired for the precipitation of high meltingpoint wax in petrolatum, or in the separation of high melting point waxfrom low melting point wax which may or may not contain a substantialpercentage of oil. As previously indicated, the precipitated waxparticles may be in any desired liquid or solid condition, either fineor coarse, or in the form of clusters, and the gravity separation of thewax and solution may be due to a relatively high density of thesolution, or to a relatively high density of the wax particles.Advantages are gained in a true counterflow wherein a rising stream ofwax particles contacts directly with a continuous descending stream ofcleansing solvent, but this condition may be reversed, and various typesof batch systems could be employed to obtain some of the advantages ofthe invention.

However, the preferred form of the invention includes a means forprecipitating wax in a solution, followed by gravity separation of waxfrom the major portion of the solution, and then cleansing the waxparticles by means of solvent which dissolves and removes undesirableportions of so-- lution carried by the wax particles. The cleansingoperation may be carried out to any desired extent, depending uponeconomic conditions or the nature of the products sought in the process.In some cases, more or less of the oil may be deliberately retained inthe wax, thereby reducing the time factor in the cleansing zone wherethe oil solution is forcibly removed from the wax particles.

In the preferred form of the invention, there is a free andcomparatively rapid gravity separation of the wax from the precipitatingsolution, and a stream of the wax particles is thereafter transmittedthrough a counterflowing stream of cleansing solvent. This results in acontinuous countercurrent extraction of the oil from the wax, involvinga counterfi-ow of the wax particles through the stream of cleansingsolvent. To most efficiently establish these conditions, thecounterflowing movements of the wax particles in the oil solution andalso in the fresh cleansing solvent, should be quite positive andcomparatively rapid. In this respect, the new process is extremelyremote from the sluggish cold settling which was superseded by thefiltering systems.

To most effectively establish and maintain the new combination ofconditions, the nature of the solvent requires special consideration,not with the idea of producing filterable wax, but to provide for thecomparatively rapid movements of the wax partic es, and other conditionsinvolved in the new process. The density or specific gravity of thesolvent is an important consideration in the step of causing the rap-idgravity separation of the wax from the solution, and also in thesubsequent step of passing the stream of wax particles through acounterfiowing stream of cleansing solution. The viscosity of thesolution and cleansing solvent even at very low temperatures, is anotherfactor that should not prevent the desired free and rapid movements ofthe wax particles. Another important property of the solvent relates tothe interfacial tension existing between the wax particles and the oilsolution, or between said wax particles and the cleansing solvent. Thisinterfacial tension is a subject separate and distinct from theviscosity, and it should not be high enough to interfere with said freeand rapid movements of the wax particles, even when the process iscarried out at very low temperatures, such as 0 R, or lower. However, wewill show that the invention is not limited to a particular solvent, asthe various properties can be obtained from numerous different solvents.

Assuming that the object is to dewax a lubrieating oil stock to producea low cold test oil, and that the wax particles are to freely rise in asolution of the oil and solvent, the following properties are preferablypresent in the solvent, or solvent blend, at the optimum operatingtemperature:

(1) An excellent oil solvent.

(2) Low solvent power for wax.

(3) A low viscosity when containing a high percentage of oil insolution.

(4) The interfacial tension existing between the wax particles and thesolvent-oil mixture must be less, as expressed in dynes per centimeter,than the work of flotation of the rising wax particles, as alsoexpressed in dynes per centimeter.

(5) The density of the solvent-oil mixture must be high enough toprovide the necessary energy differential between the interfacialtension and the buoyancy.

A single solvent having all of these properties may be employed, or theseveral difierent conditions may be obtained by using a plurality ofsoliii 'i. dichlorethyl ether.

vents each having one or more, but not all of the desired properties.

Continuing this illustration, and assuming that one desires to obtainthe additional advantage of avoiding the hazards as to fire andexplosion involved in using the solvents that have become most popularin the modern filtering processes, any of the following solvent blendsmay be employed in the new process:

56% carbon tetrachloride and 50% acetone.

50% perchlorethylene, 40% isopropyl acetate and 10% dichlorethyl ether.

Other illustrations include methylene dichloride with acetone, or withisopropyl acetate and Tetrachlorethane with acetone. Trichlorethane withacetone and furfural. Ethylene dichloride with ethyl acetate anddichlorethyl ether. For convenience in commercial practice, methylenedichloride and dichlorethyl ether (chlorex) provide a desirablecombination of only two solvents.

However, the present invention is not limited to any particular solvent.The use of such solvents claimed in an application for patent filed by'Oswald G. Mauro and Eddie M. Dons on Novemher 2, 1939, Serial Number302,508.

The accompanying drawing is a diagrammati cal view of a system which maybe employed to carry out one form of the invention.

A continuous stream of the wax-bearing charging stock, for example, alubricating oil stock, enters the system through a pipe l which may, beprovided with a heater 2. A continuous stream of cool dewaxing solvent,from a source to be hereafter described, is conducted through a pipe 3and heat exchanger i to the oil supply pipe I. The continuous streams ofheated oil and cooled solvent are united in the pipe 5 and transmittedthrough a mixing nozzle 5 where the oil and solvent are mixed at atemperature high enough to form the desired solution.

The continuous stream of solution is transmitted through the heatexchanger t for additional cooling. Thereafter, the stream of solutionpasses through a cooler, or chiller, l where the flowing solution iscooled to a temperature desired for precipitation of wax therein.

If desired, the resultant mixture of solution and precipitated may betransmitted into comminuting device 8 including a rotary breaker 9whereby the wax is forcibly divided into minute particles suspended inthe chilled solution to form an approximately homogeneous slurry of waxand said solution. A pipe it conducts a,

continuous stream of the wax particles and solution to a flaringdischarge nozzle i l in the lower portion of a separating chamber 52.This chamber may be in the form of an upright column covered withinsulation it.

The incoming stream of chilled solution and wax particles may bedelivered to the separating chamber 2 at approximately the temperatureselected for precipitation of wax in the cooler, or chiller, T. Forexample, this temperature may be about 0 F., and We prefer to insulatethe chamber i2 so as to maintain the desired extracting and cleansingtemperatures therein, as this avoids the necessity of providing acooling jacketaround the chamber. In fact, an advantage is gained byavoiding excessive cooling of -the walls of said chamber, as suchcooling would tend to produce an adhesive condition in the.

wax at said walls, thereby interfering with the desired free movementsof the wax.

We are assuming that a relatively dense solvent has been selected forthis operation, and that the viscosity and interfacial tension are lowenough to allow the wax particles to freely rise in the dense solution.In this event, the major portion of the dense solution will freely movedownwardly to the bottom of the column where it is discharged through apipe I4. This outgoing solution is free of wax and it can be distilledin any suitable manner to remove the solvent from the dewaxed oil.However, before leaving the dewaxing system, it can be convenientlytransmitted through the heat exchanger 6 to aid in cooling the incomingsolution.

Attention is now directed to the separating zone, or extracting zoneestablished near the point where the incoming mixture of solvent and waxenters the column I2. The mass of wax particles move upwardly and carrywith them portions of the solution, including oily fihns around the waxparticles and relatively free portions of the solution between therising wax particles. However, this rising mass enters into a relativelyheavy descending stream produced by continuously introducing a stream ofcleansing solvent through a pipe l leading into the upper portion of thecolumn I 2. This incoming cleansing solvent may pass through a cooler l5which cools it to the desired operating temperature. It will beunderstood that the cleansing solvent has the previously mentionedrequirements as to density, viscosity and interfacial tension, and thatit will readily dissolve the oil without dissolving the wax.

Therefore, the stream of cleansing solvent will freely descend in directcontact with the rising stream of wax particles, so as to dissolve thefree portions of oil solution carried by the wax, and also forciblyscrub the oily films from the rising wax particles. A free counterflowof this kind does not break said rising wax particles into finerparticles, and does not produce a violent artificial disturbance thatwould impair the natural cleansing flow due to different specificgravities of the counterflowing streams. However, the cleansing actionmay be aided by any suitable mechanical appliance. For example, a rotaryagitator I! having arms l3 may be located in the upper portion of thecolumn l2 to forcibly move the counterfiowing streams into intersectingpaths.

The velocity and time of this cleansing action may be regulated toseparate all of the oil from the wax, or any desired percentage of oilmay be carried along with the wax, depending upon the commercialrequirements. The scrubbed wax particles are discharged in the form of aslurry through a pipe l9 leading from the top of the chamber I2 whererotary blades 20 on the shaft of agitator I! tend to centrifugally impelthe slurry toward the outlet. This outgoing material can be immediatelyconducted to storage through a pipe 2| However, in the specific exampleillustrated in the drawing, the pipe [9 leads to a supplementalcleansing chamber in the form of a column 22, covered with insulation23, and having an inlet near the top for a stream of solvent whichenters through a pipe 24. This solvent conforms to the requirementsheretofore pointed out, and it may be cooled to the operatingtemperature by passing through a cooler or chiller 25.

The wax particles rise through the descending stream of fresh solvent inthe supplemental cleansing column 22, thereby more completely washingaway traces of oil carried with the wax. The descending solventcontaining a small percentage of oil, can be conveniently transmittedthrough the pipe 3 leading from the bottom of column 22 to the incomingstream of oil in the pipe I. The incoming fresh solvent can be thusemployed to very effectively cleanse the outgoing Wax before saidsolvent enters into the stream of incoming oil. Another advantageappears in the convenient recovery of a small percentage of valuable oilwhich is carried by the solvent to the incoming supply of oil.

The supplemental cleansing chamber 22 may be provided with a rotaryagitator 26 having arms 2?, and if desired, a heater 28 may be locatedin the upper end of said chamber to liquefy the outgoing wax. The use ofthis heater depends upon the results desired, bearin in mind that someof the solvent will pass out with the wax, and traces of oil may befound in this solvent. This outgoing Wax product, while still in a coldcondition can be subjected to a simple straining or filtering operationfor the purpose of separating free liquid from the wax. For example, thewax slurry may be discharged through a pipe 29 leading to a strainer 38where free solvent is separated from the wax product which passes outthrough a conductor 3| while the solvent is discharged through a pipe32. This solvent can be conducted to storage through a pipe 33. However,it is not likely to be contaminated by any material objectionable in theprocess, and even if it should contain traces of oil, there would be acorresponding advantage in returning the oil to the incoming supply.Therefore, the solventrecovery pipe 32 preferably leads to the pipe 3which conducts the recovered solvent to the incoming stream of chargingoil,

The conditions as to temperature, velocity, etc., in the supplementalcleansing column 22 can be separately regulated to accurately controlthe degree of cleansing, thereby providing for any desired degree ofpurity in the wax, and at the same time avoiding undue escape of oilwhich in some cases is the most valuable product. Moreover, the refiningoperations accurately controlled in this manner tend to reduce the totalmanufacturing cost of the refined oil and wax.

The temperatures in the separating zone and cleansing zones may beapproximately the same as the temperature at which the wax isprecipitated in the original solution, but variations in thetemperatures are permissible where they do not result in objectionablechanges in the condition of the wax particles,

At these temperatures, the selected wax particles are precipitated inany suitable solution having the required properties, and thereaftersubjected to any suitable cleansing solvent having an affinity for thesolution greater than the amnity of the wax for said solution.Furthermore, when this apparatus is employed to dewax oils havingparafiinic and naphthenic constituents, the precipitating solvent willhave an aflinity for the oil greater than the afiinity of the wax forthe parafl'inic oil constituents, so as to dissolve the parafiinic oilwithout dissolving the paraffinic wax.

As a specific example, we will refer to the dewaxing of petroleumlubricating oil wherein the solvent employed in precipitatin the wax isthe same as the solvent employed to cleanse the wax particles. In actualpractice, it is usually most convenient to use the same solvent blendthroughout the system.

Assuming that the solvent blend consists of 50% carbon tetrachloride and50% acetone, and that the oil to be dewaxed is a waxy bright stockhaving a cloud point of about 70 F., a pour point of about 60 F., aviscosity of 100 at 210 F., and containing about 10% to 12% wax, we havefound that the following results can be obtained.

Using one volume of oil and two volumes of precipitating solvent, andchilling the resultant solution to F., the dewaxed oil had a pour pointequal to or about or F. lower than -said chilling temperature, and acloud point b-clow 30 F., showing that all of the objectionable wax wasremoved. In this specific example, the supplemental cleansing chamber 22was not available. Two volumes of the cleansing solvent was introducedinto the upper portion of a single stage cleansing zone, and the dewaxedsolution consisted of about 3 /2 Volumes of solvent with about 86% to88% of the original waxy oil charge. The purified wax product dischargedfrom the single stage cleansing zone amounted to about 12% to 14% of theoriginal charge with about one-half of a volume of solvent serving as acarrier for the cleansed wax particles.

We claim:

1. In an apparatus for separating wax from lubricating oil wherein acontinuous stream of the wax-bearing oil is mixed with a continuousstream of selective dewaxing solvent and chilled to precipitate solidwax particles lighter than the chilled solution, a substantially uprightinsulated separating chamber having an inlet for the stream of chilledmixture of solution and wax particles, means for forcibly breaking thewax particles in the last mentioned stream before it enters saidseparating chamber, said separating chamber having an outlet lower thansaid inlet to provide for the discharge of the descending relativelyheavy dewaxed solution, and a wax outlet higher than said inlet toprovide for the discharge of a relatively light slurry of wax,solventand oil, means for transmiting a chilled stream of relativelyheavy cleansing solvent into said separating chamber at a point betweenthe first mentioned inlet and said wax outlet, so as to separate oilyliquid from the rising wax particles before they reach said wax outlet,a rotary impelling member located near said wax outlet to centrifugallyforce the wax slurry toward said wax outlet, an insulated supplementalcleansing chamber communicating with said wax outlet and having an inletfor said wax slurry, said supplemental cleansing chamber being providedwith a wax outlet higher than said inlet for the wax slurry, a strainingdevice communicating with the last mentioned wax outlet to separateliquid from the outgoing mass of wax particles, means for introducing acontinuous stream of chilled solvent into said supplemental cleansingchamber at a point between its inlet for the wax slurry and its higherwax outlet, a conductor leading from a lower portion of saidsupplemental cleansing chamber to said continuous stream of wax bearingoil to complete the first mentioned mixture of streams, a heat exchangerthrough which said first mentioned mixture is transmitted in heatexchange relationship with the last mentioned conductor, and a secondheat exchanger comprising a conductor through which heavy dewaxedsolution from the first mentioned outlet is transmitted into heatexchange relationship with the first mentioned mixture of streams,

oil

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2. In an apparatus for continuously dewaxing oil and deoiling the wax,means for dissolvin wax-containing oil in a selective dewaxing solvent,a cooler wherein the solution is cooled to precipitate wax in the liquidsolution of oil and solvent, dewaxing means whereby the major portion ofsaid liquid solution is immediately released from the wax and therebydewaxed without requiring filtration of said major portion or" thesolution, said dewaxing means including a separating chamber having aninlet communicating with said cooler to receive the mixture of liquidsolution and wax, said separating chamher also having an outlet for thedewaxed solution lower than said inlet to provide for imme diatedischarge of relatively heavy dewaxed solution, and a wax outlet higherthan said inlet to provide for the discharge of relatively light wax, adeoiling zone for the rising stream of wax being formed between saidinlet and the higher wax outlet, means for introducing a descendingstream of relatively heavy cleansing solvent into the rising stream ofwax particles in said deoiling zone, said deoiling zone providing freepaths for the cleansing flow due to different specific gravities of theintersecting streams, a supplemental cleansing chamber communicatingwith said wax outlet and having an inlet for said wax, said supplementalcleansing chamber being provided with a wax outlet higher than the lastmentioned inlet, a supplemental deoiling zone being, formed between thelast mentioned outlet and inlet, and means for introducing a stream ofrelatively heavy cleansing solvent into said supplemental deoiling zone,a lower portion of said supplemental cleansing chamber being providedwith an outlet communicating with the first mentioned inlet, so as totransmit the outgoing cleansing solvent from said supplemental deoilingzone to the incoming wax-containing oil.

3, In an apparatus for continuously dewaxing oil and deoiling the wax,means for dissolving wax-containing oil in a selective dewaxing solvent,a cooler wherein the solution is cooled to precipitate wax in a liquidsolution of oil and solvent, while trapping portions of said liquidsolution the precipitated wax, breaking means associated with saidcooler to forcibly break the wax into minute particles in said liquidsolution, thereby liberating trapped oil solution from the wax, dewaxingmeans whereby the major portion of said liquid solution is released fromthe broken wax particles and thereby dewaxed without requiringfiltration of said major portion of the solution, said dewaxing meansincluding a separating chamber having an inlet communicating with saidbreaking means to receive the mixture of liquid solution and broken waxparticles, said separating chamber also having an outlet for the dewaxedsolution lower than said inlet to provide for the discharge ofrelatively heavy dewaxed solution, and a wax outlet higher than saidinlet to provide for the discharge o relatively light wax, a deoilingzone for the rising stream of broken wax particles being formed betweensaid inlet and the higher wax outiet, means for introducing 'adescending stream of relatively heavy cleansing solvent into the risingstream of wax particles in said deoiling zone.

4. In an apparatus for dewaxing lubricating oil and then deoiling thewax, a wax-precipitating device including a chiller wherein the wax isprecipitated, means for transmitting a liquid solution of dewaxingsolvent and wax-bearing lubricating oil to said chiller, so as toprecipitate wax while trapping portions of the liquid solution in thewax, a comminuting device for forcibly breaking the precipitated waxinto minute particles in the chilled liquid solution, so as toimmediately liberate trapped liquid solution from the wax, releasingmeans whereby the major portion of said liquid solution is released anddropped from the broken wax particles, said releasing means including aseparating chamber having an inlet communicating with said comminutingdevice to receive the chilled mixture of solution and broken waxparticles, said separating chamber also having an outlet lower than saidinlet to provide for immediate discharge of relatively heavy dewaxedsolution, and a wax outlet higher than said inlet to provide for thedischarge of the relatively light wax particles, a deoiling zone for therising stream of broken wax particles being formed between said inletand the higher Wax outlet, and means for introducing a descending streamof relatively heavy cleansing solvent into the rising mass of waxparticles in said deoiling zone.

5. In an apparatus for continuously dewaxing lubricating oil and thendeoiling the wax, means for dissolving wax-containing lubricating oil ina selective dewaxing solvent, a chiller wherein the solution is cooledto precipitate wax in a liquid solution of oil and solvent, whiletrapping portions of said liquid solution in the wax, breaking meansassociated with said chiller to forcibly break the precipitated wax intominute particles in said liquid solution, thereby positively liberatingtrapped oil solution from the wax, dewaxing means whereby the majorportion of said liquid solution is dropped from the broken wax particlesand thereby dewaxed, said dewaxing means including a settling zonehaving an inlet communicating with said breaking means to receive themixture of liquid solution and broken wax particles, said settling zonealso having an outlet for the dewaxed solution lower than said inlet toprovide for the discharge of relatively heavy dewaxed solution, deoilingmeans comprising a countercurrent deoiling zone communicating with saidsettling zone to receive the broken wax particles, and means fortransmitting a descending stream of relatively heavy deoiling solventthrough a rising stream of the wax particles in said countercurrentdeoiling zone, so as to remove oily solvent from said broken waxparticles.

6. In an apparatus for continuously dewaxing oil and deoiling the wax,means for dissolving wax-containing oil in a selective dewaxing solvent,a cooler wherein the solution is cooled to precipitate wax in a liquidsolution of oil and solvent, while trapping portions of the liquidsolution in the precipitated wax, breaking means associated with saidcooler to forcibly break the wax into minute particles in said liquidsolution, thereby liberating trapped oil solution from the wax, dewaxingmeans whereby the major portion of said liquid solution is released fromthe broken wax particles and thereby dewaxed without requiringfiltration of said major portion of the solution, said dewaxing meansincluding a separating chamber having a settling zone provided with aninlet communicating with said breaking means to receive the mixture ofliquid solution and broken wax particles, said separating chamber alsohaving an outlet for the dewaxed solution lower than said inlet toprovide for the discharge of relatively heavy dewaxed solution, and awax outlet higher than said inlet to provid for the discharge ofrelatively light wax, a supplemental cleansing chamber having a deoilingzone communicating with said Wax outlet, and means for introducing adescending stream of relatively heavy deoiling solvent into a risingstream of the lighter wax particles in said deoiling zone, so as toseparate dissolved oil from the outgoing mass of wax.

EDDIE M. DONS. OSWALD G. MAURO.

